Description
The EM4058 earth tester is a digital, microprocessor-controlled instrument that allows for measuring earth resistance and ground resistivity (using Wenner's method), as well as detecting parasitic voltages present in the ground. This instrument is suitable for measuring earth systems in power substations, industries, distribution networks, etc., according to IEC 61557-5.
It is also suitable for soil resistivity measurements to optimize the earth systems project. It is a fully automatic and easy-to-operate device. Before starting each measurement, the equipment will check that conditions are within appropriate limits and notify the operator if any abnormalities are detected (e.g., too high interference voltage, excessive resistance in test spikes, very low test current, etc.). Then, it will find the most suitable range and display the results on an alphanumeric display.
To conveniently test the earth system, the EM4058 allows for measurements using a test current with a frequency that can be operator-selected (270 Hz, 570 Hz, 870 Hz, 1170 Hz, or 1470 Hz). The lowest frequency allows for analysis of earth system behavior related to fault currents of industrial frequency, while the highest frequency provides insights into behavior concerning electrical currents caused by lightning and offers high immunity to interference voltages, especially near substations.
The EM4058 features a frequency scan, which automatically performs earth resistance measurements at all available frequencies, calculates, displays, and prints the average result alongside individual results for each frequency. These results are stored in the internal memory.
The instrument has four automatically selected ranges, covering measurements from 0.01 Ω up to 20 kΩ, ensuring accurate measurements for various soil types. During ground resistivity measurement, the operator can input the distance between spikes, allowing the equipment to apply Wenner's formula and directly display the resistivity value.
The EM4058 includes built-in memory for storing measurements and a built-in printer, as well as a USB interface to download measured values to a computer or data logger for further analysis. It also features a remote interface for control via an Android device. The device is portable, durable, lightweight, and suitable for field use in severe weather conditions. It is powered by a rechargeable LFP battery and comes with all necessary accessories (test spikes, leads, etc.) in a convenient auxiliary carrying case.
Technical Specifications
Operation frequency
270 Hz (resistance or resistivity measurement).
570 Hz, 870 Hz, 1170 Hz, or 1470 Hz (resistance measurement).
Max. variation: ± 1 Hz (both cases).
Voltmeter
In voltmeter mode, the device operates as a conventional voltmeter, enabling measurement of voltages generated by parasitic currents.
Measurement ranges
Resistance: 0-20 Ω; 0-200 Ω; 0-2000 Ω; and 0-20 kΩ (auto-ranging).
Resistivity: 0-50 kΩm (auto-ranging).
Voltage: 0-60 V~.
Accuracy
Resistance and resistivity measurements:
R ≤ 2 kΩ: ± (2 % of the measured value ± 2 digits).
R > 2 kΩ: ± (5 % of the measured value ± 2 digits).
Voltage measurement:
± (3 % of the measured value ± 2 digits).
Reading resolution
0.01 Ω in resistance measurement;
0.01 Ωm in resistivity measurement;
0.1 V in voltage measurement.
Output current
Short-circuit current is limited to less than 20.0 mARMS (in accordance with IEC 61557-5 - 4.5).
Immunity to spurious voltage interference
During resistance measurement, the device tolerates spurious voltages up to 7 V~, with an error < 10 %.
Earth resistance of auxiliary rods
During resistance measurement, the device tolerates auxiliary rod resistance (RAUX) up to 50 kΩ with an error < 30 %.
Advanced features
Automated detection of abnormal conditions that may cause excessive errors (e.g., low battery, high noise interference, high test spike resistance).
Soil resistivity computing
During soil resistivity measurements, the operator inputs the distance between spikes, and the EM4058 automatically computes soil resistivity using Wenner's full equation.
Interface
USB.
Built-in printer
Provides a printed record of measured values.
Power supply
Internal rechargeable LFP battery (LiFePO4 12 V - 3000 mAh).
Battery charger
AC Adapter (12 V - 2.0 A).
Safety class
In accordance with IEC 61010-1.
E.M.C.
In accordance with IEC 61326-1.
Electrostatic immunity
In accordance with IEC 61000-4-2.
Electromagnetic irradiation immunity
In accordance with IEC 61000-4-3.
Environmental protection
IP65 (with closed lid).
Operation temperature
14 °F to 122 °F (-10 °C to 50 °C).
Storage temperature
-13 °F to 158 °F (-25 °C to 70 °C).
Humidity
95 % RH (without condensation).
Equipment weight
Approx. 6.61 lb (3 kg).
Dimensions
10.78" x 9.84" x 4.88" (274 x 250 x 124 mm).
